With the advent of portable wireless digital radiography (DR) detectors, hospitals and other healthcare facilities now have expanded capability for obtaining x-ray images, including images obtained at the patient bedside. Unlike conventional radiographic image detectors, the wireless DR detectors can be positioned about the patient in a number of positions, without the concern for extending wires between the detector and image acquisition and power electronics. Portability with wireless operation also makes these devices suitable for use in veterinary imaging, since the DR detector can be flexibly positioned and there are no external wires that could be chewed or otherwise damaged during handling and positioning about the animal subject. It is also possible to use the DR detector in various outdoor environments, under a range of weather conditions.
In conventional use as well as in veterinary, outdoor, and industrial and security imaging environments, however, the portable DR detector can be susceptible to ingress of bodily liquids, chemical liquids in the imaging area, and moisture. Even with careful sealing and liquid ingress prevention techniques, there still exists some risk to the detector if moisture or bodily fluids are able to seep into the housing interior and interfere with internal detector circuitry. To combat this problem, DR detector design may make use of a number of seals, o-rings, gaskets, and similar features intended to prevent moisture ingress. This adds cost and complexity to the mechanical design of the DR detector. Gasketed surfaces, for example, need to be meticulously ground and polished and mating surfaces must meet tight tolerances for uniformity, with a significant number of fasteners properly tightened in order that seals function properly. Reassembly requires considerable care in the event that the detector is disassembled for replacement of a battery or other component.
Encasement of the detector in a plastic envelope or other waterproof sleeve is a poor solution to the problem. Conventional liquid-tight sealing methods are also air-tight, sealing in heat and potentially causing an overheating condition that can degrade the life of electronic components and performance. In addition, some methods for obtaining a liquid-tight seal can compromise wireless signal transmission and reception.
Conventional liquid-proofing methods may be unsatisfactory solutions for a number of reasons. Gaskets and seals exhibit wear over time and their performance can be degraded by various factors, such as by disinfectant solutions and exposure to ultraviolet (UV) light, for example. Encasement of the detector within a container or envelope is not a suitable solution for every environment and would require constant replacement of the containment device. Standard sealant coatings would have a limited applicability and lifetime, subject to damage from scratching and abrasion. Moreover, a complete seal would not be feasible with many DR detectors, because there may be some type of input/output port provided for connecting data transfer wires, power cables, and connectors for other functions.
Levels of water resistance for electrical equipment and components are typically described by an IPX-rating, as defined in ANSI/IEC (American National Standards Institute/International Electrotechnical Commission) test specification ANSI/IEC 60529-2004 entitled “Degrees of Protection Provided by Enclosures”. In the IPX rating system, a scale of values indicates relative protection from moisture, with higher values indicating correspondingly higher levels of protection. For example, a value of IPX-0 indicates virtually no protection from water. A value of IPX-4 indicates protection against splashing. A value of IPX-6 indicates protection against a high-pressure water stream. A value of IPX-8 indicates protection under continuous submersion. It can be appreciated that it would be beneficial to provide a high level of protection against liquid ingress for a DR detector, without adding significant cost, weight, or complexity to the device. At the same time, waterproofing and liquid proofing methods should have little or no impact on performance and functional requirements of the DR detector device related to sensitivity, image quality, interoperability, cooling, electrical connection, and component accessibility.